The present invention relates to a method for preparing a ZnO nanocrystal directly on a silicon substrate, more specifically, to a method for preparing a ZnO nanocrystal directly on a silicon substrate, including the steps of: forming a Zn—Si—O composite thin film on the silicon substrate (S1); and performing a heat treatment on the obtained film (S2).
In general, nanosize (nm, 10−9 m) materials differ from the same materials but in macrosize by physical and chemical properties. Because of a large surface area-mass ratio, nanosize materials can be applied to a photocatalyst using chemical reactions that occur at the surface and an optoelectronic device using optical properties due to surface defects.
Moreover, ZnO can stably emit UV light by exciton due to its broad direct energy bandgap of 3.36 eV and large exciton binding energy of 60 meV at room temperature. These excellent optical properties have caused a lot of interest in ZnO for optoelectronic applications such as ultraviolet LED or LD.
Among many structural configurations (single crystal, thin film, low-dimensional nanostructure, etc.), researches have recently been actively undertaken on a fabrication method of ZnO of low-dimensional nanostructure in relation to nano-optoelectronic devices. ZnO nanocrystals, one of low-dimensional nanostructure configurations, are fabricated primarily by chemical approaches (A. V. Dijken at al, J of Luminescence 90, 123-128 (2000); R. Viswanatha et al, J of Materials Chemistry 14, 661-668 (2004); K. Lin et al, Appl. Phys. Lett. 88, 263117-1˜3 (2006)). However, ZnO nanocrystals prepared by chemical approaches exist in solution-phase, so an additional process, i.e., coating the nanocrystals over a silicon substrate is required to produce an optoelectronic device based on the silicon substrate.